The overall objective of this research will be to specify behavioral and pharmacological factors that determine how drugs alter behavior. The proposed research will deal particularly with behavior controlled by scheduled presentation of electric shocks or other scheduled noxious stimuli. Both the maintenance and the suppression of behavior by such schedules will be investigated. Dose-effect relationships will be established by pretreatment with representative drugs; the behavioral and pharmacological consequences of chronic administration of selected drugs will be studied. The effects of drugs on interrelations between schedule-controlled performances and changes in heart rate and blood pressure also will be studied. Patterns of behavior have been developed and maintained in the squirrel monkey under conditions in which responses produced noxious stimuli. The importance of experimental history, the schedule, and schedule parameter values in engendering and maintaining this significant behavior will be studied. These studies of patterns of behavior controlled by schedules of presentation or termination of various events will provide critical data on the role of factors such as experimental history, schedule of reinforcement, level of ongoing behavior, and type of event maintaining the behavior as determinants of the behavioral effects of drugs.